Liquid crystal display

ABSTRACT

A liquid crystal display is provided. The liquid crystal display includes a first display substrate, a second display substrate which faces the first display substrate, and a liquid crystal layer which is disposed between the first display substrate and the second display substrate. The first display substrate comprises a first base substrate, a reflective electrode which is disposed on the first base substrate, and a pixel electrode which is disposed on the reflective electrode. The second display substrate comprises a second base substrate, a color filter layer which comprises a first color filter disposed on a surface of the second base substrate which faces the first base substrate and a second color filter configured to display a different color from the first color filter, a protruding pattern which is formed on a surface of the color filter layer facing the first base substrate and which extends along a boundary between the first color filter and the second color filter, and reflective members which are disposed on sidewalls of the protruding pattern.

This application claims the benefit of Korean Patent Application No.10-2016-0128106, filed on Oct. 5, 2016, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND 1. Field

The present inventive concept relates generally to a liquid crystaldisplay (LCD), and more particularly, to a reflective LCD.

2. Description of the Related Art

A liquid crystal display (LCD) is a display device that displays animage by controlling light transmittance or reflectivity, in turn bycontrolling the molecular alignment state of liquid crystals. LCDsconsume low power and are lightweight. Therefore, LCDs are widely usedfor various devices ranging from small-sized devices such as mobilephones, digital cameras and portable information devices to large-sizedmonitors and TVs.

LCDs can be divided into transmissive LCDs and reflective LCDs accordingto the light source used. A transmissive LCD displays an image bytransmitting light emitted from a backlight module through a liquidcrystal panel, and a reflective LCD displays an image using externallight reflected by a liquid crystal panel.

The transmissive LCD has low light utilization efficiency because onlyabout ⅕ of the light emitted from the backlight module passes throughthe liquid crystal panel, and has high power consumption because morethan ⅔ of the total power is consumed in the backlight module. On theother hand, the reflective LCD uses external light instead of employinga separate light source. Therefore, power consumption is minimized.

In general, the reflective LCD includes a first display substrateincluding a switching device, a pixel electrode and a reflective layer,a second display substrate including a common electrode, a color filterand a light blocking member, and a liquid crystal layer interposedbetween the first display substrate and the second display substrate.Here, the light blocking member of the second display substrate ispositioned at a boundary portion of each pixel to prevent the leakage oflight and improve a reflection contrast ratio.

The light blocking member reduces an aperture ratio of the reflectiveLCD due to its light blocking property. Thus, a reflective LCD withoutthe light blocking member has been proposed.

However, if the light reflective member is omitted, a boundary betweenadjacent pixels is not completely hidden. Therefore, a mixture of twocolors displayed respectively by the adjacent pixels may be displayedaround the boundary between the adjacent pixels.

SUMMARY

Aspects of the inventive concept provide a liquid crystal display (LCD)in which color mixture is reduced or minimized.

However, aspects of the inventive concept are not restricted to the onesset forth herein. The above and other aspects of the inventive conceptwill become more apparent to one of ordinary skill in the art to whichthe inventive concept pertains by referencing the detailed descriptionof the inventive concept given below.

According to an aspect of the inventive concept, there is provided aliquid crystal display. The liquid crystal display comprises a firstdisplay substrate, a second display substrate which faces the firstdisplay substrate, and a liquid crystal layer which is disposed betweenthe first display substrate and the second display substrate. The firstdisplay substrate comprises a first base substrate, a reflectiveelectrode which is disposed on the first base substrate and a pixelelectrode which is disposed on the reflective electrode. The seconddisplay substrate comprises a second base substrate, a color filterlayer which comprises a first color filter disposed on a surface of thesecond base substrate which faces the first base substrate and a secondcolor filter displaying a different color from that of the first colorfilter, a protruding pattern which is formed on a surface of the colorfilter layer facing the first base substrate and which extends along aboundary between the first color filter and the second color filter, andreflective members which are disposed on sidewalls of the protrudingpattern.

According to other aspect of the inventive concept, there is provided aliquid crystal display. The liquid crystal display comprises a firstdisplay substrate, a second display substrate which faces the firstdisplay substrate, and a liquid crystal layer which is disposed betweenthe first display substrate and the second display substrate. The firstdisplay substrate comprises a first base substrate, a reflectiveelectrode which is disposed on the first base substrate, a pixelelectrode which is disposed on the reflective electrode, a protrudingpattern which is disposed on the pixel electrode and reflective memberswhich are disposed on sidewalls of the protruding pattern. The seconddisplay substrate comprises a second base substrate and a color filterlayer which comprises a first color filter disposed on a surface of thesecond base substrate which faces the first base substrate and a secondcolor filter configured to display a different color from that of thefirst color filter, wherein the protruding pattern extends along aboundary between the first color filter and the second color filter.

According to the other aspect of the inventive concept, there isprovided a liquid crystal display. The liquid crystal display comprisesa first display substrate, a second display substrate which faces thefirst display substrate, and a liquid crystal layer which is disposedbetween the first display substrate and the second display substrate.The first display substrate comprises a first base substrate, an organicfilm which is disposed on the first base substrate and which comprises aflat portion having a flat upper surface and a protruding portionprotruding from the flat portion toward the second display substrate, areflective electrode which comprises a first reflective portion disposedon the flat portion and second reflective portions disposed on sidewallsof the protruding portion and a pixel electrode which is disposed on thereflective electrode. The second display substrate comprises a secondbase substrate, and a color filter layer which comprises a first colorfilter disposed on a surface of the second base substrate that faces thefirst base substrate and a second color filter configured to display adifferent color from that of the first color filter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a layout view of a pixel of a liquid crystal display (LCD)according to an embodiment;

FIG. 2 is a cross-sectional view taken along the line I-I′ of FIG. 1;

FIG. 3, FIG. 4, FIG. 5 and FIG. 6 are cross-sectional views illustratinga method of manufacturing an LCD according to an embodiment;

FIG. 7 is a cross-sectional view of an LCD according to an embodiment,taken along the line I-I′ of FIG. 1;

FIG. 8 is a cross-sectional view of an LCD according to an embodiment,taken along the line I-I′ of FIG. 1; and

FIG. 9, FIG. 10, FIG. 11 and FIG. 12 are cross-sectional viewsillustrating a method of manufacturing an LCD according to anembodiment.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fillyconvey the scope of the invention to those skilled in the art. The samereference numbers indicate the same components throughout thespecification. In the attached figures, the thickness of layers andregions is exaggerated for clarity.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms are only used todistinguish one element from another element. Thus, a first elementdiscussed below could be termed a second element without departing fromthe teachings of the invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “Or” means “and/or.” As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

All numerical values are approximate, and may vary. All examples ofspecific materials and compositions are to be taken as nonlimiting andexemplary only. Other suitable materials and compositions may be usedinstead.

In the present invention, an electronic apparatus may be any apparatusprovided with a display device. Examples of the electronic apparatus mayinclude smart phones, mobile phones, navigators, game machines, TVs, carhead units, notebook computers, laptop computers, tablet computers,personal media players (PMPs), and personal digital assistants (PDAs).The electronic apparatus may be embodied as a pocket-sized portablecommunication terminal having a wireless communication function.Further, the display device may be a flexible display device capable ofchanging its shape.

Hereinafter, embodiments of the present invention will be described withreference to the attached drawings.

FIG. 1 is a layout view of a pixel of a liquid crystal display (LCD)according to an embodiment, and FIG. 2 is a cross-sectional view takenalong the line I-I′ of FIG. 1.

Referring to FIGS. 1 and 2, the LCD according to the current embodimentincludes a first display substrate 100, a liquid crystal layer 200, anda second display substrate 300.

A switching device (e.g., a thin-film transistor 167) for driving liquidcrystals 210 of the liquid crystal layer 200 is disposed in the firstdisplay substrate 100. The second display substrate 300 is a substratedisposed opposite to the first display substrate 100.

The liquid crystal layer 200 may be interposed between the first displaysubstrate 100 and the second display substrate 300, and may include aplurality of liquid crystals 201 having a dielectric anisotropy. When anelectric field is applied between the first display substrate 100 andthe second display substrate 300, the liquid crystals 210 may rotate ina specific direction between the first display substrate 100 and thesecond display substrate 300, thereby transmitting or blocking light.Here, the term “rotate” may denote not only that the liquid crystals 210actually rotate, but also that the arrangement of the liquid crystals210 is changed by the electric field.

The LCD includes a plurality of pixels 10 arranged in a matrix form.Respective gray levels of the pixels 10 may be controllableindependently of each other, and each of the pixels 10 may be a basicunit for displaying a specific color. In FIG. 1, a pixel 10, part ofanother pixel 10 x disposed on a left side of the pixel 10, and part ofanother pixel 10 y disposed on a right side of the pixel 10 areillustrated. Since the three pixels 10, 10 x, and 10 y havesubstantially the same structure, the pixel 10 located in the middlewill be mainly described.

The first display substrate 100 will hereinafter be described.

The first display substrate 100 includes a first base substrate 110.

The first base substrate 110 may be an opaque insulating substrate.However, the first base substrate 110 is not necessarily an opaqueinsulating substrate and can also be a transparent insulating substrate.

In some embodiments, the first base substrate 110 may be curved along adirection. In some other embodiments, the first base substrate 110 mayhave flexibility. That is, the first base substrate 110 can be deformedby rolling, folding, bending, or the like.

A gate line 122, a gate electrode 124, and a storage line 125 aredisposed on the first base substrate 110.

The gate line 122 carries a gate voltage for controlling the thin-filmtransistor 167. The gate line 122 may extend in a first direction D1.

Here, the first direction D1 is a direction perpendicular to a seconddirection D2 and a direction extending parallel to a side of the firstbase substrate 110. In addition, the first direction D1 can be definedas a direction indicated by an arbitrary straight line extending fromthe left side toward the right side as illustrated in FIG. 1. The seconddirection D2 can be defined as a direction indicated by an arbitrarystraight line extending from an upper side toward a lower side asillustrated in FIG. 1.

The gate voltage may be provided from an external source, and may have avarying level. The level of the gate voltage may control the thin-filmtransistor 167 to be turned on or off.

The gate electrode 124 may protrude from the gate line 122 and may bephysically connected to the gate line 122. The gate electrode 124 may beone component of the thin-film transistor 167 which will be describedlater.

The storage line 125 is disposed between each pair of gate lines 122.The storage line 125 may extend substantially along the first directionD1 and may be formed to have a predetermined area in each pixel 10, soas to maximize an overlap area with a storage electrode 168 which willbe described later. A predetermined capacitance may be formed betweenthe storage electrode 168 and the storage line 125, thereby preventing asharp drop in the voltage level of a pixel electrode 191 which isconnected to the storage electrode 168.

The gate line 122, the gate electrode 124, and the storage line 125 maybe made of the same material. In an example, the gate line 122, the gateelectrode 124, and the storage line 125 may be made of an aluminum(Al)-based metal such as aluminum or an aluminum alloy, a silver(Ag)-based metal such as silver or a silver alloy, a copper (Cu)-basedmetal such as copper or a copper alloy, a molybdenum (Mo)-based metalsuch as molybdenum or a molybdenum alloy, chrome (Cr), titanium (Ti), ortantalum (Ta). Each of the gate line 122, the gate electrode 124, andthe storage line 125 may have a single layer structure or a multilayerstructure including at least two conductive films having differentphysical properties.

A gate insulating film 130 is disposed on the gate line 122, the gateelectrode 124, and the storage line 125. The gate insulating film 130may be made of an insulating material such as silicon nitride or siliconoxide. The gate insulating film 130 may have a single layer structure ora multilayer structure including two gate insulating layers 130 havingdifferent physical properties.

A semiconductor layer 140 is disposed on the gate insulating film 130.At least part of the semiconductor layer 140 may overlap the gateelectrode 124. The semiconductor layer 140 may be made of amorphoussilicon, polycrystalline silicon, or an oxide semiconductor.

The semiconductor layer 140 may overlap not only the gate electrode 124but also a data line 162, a source electrode 165 and a drain electrode166 which will be described later.

Although not illustrated in the drawings, ohmic contact members may beadditionally disposed on the semiconductor layer 140 in someembodiments. The ohmic contact members may be made of n+ hydrogenatedamorphous silicon doped with an n-type impurity at a high concentration,or may be made of silicide. The ohmic contact members may be disposed onthe semiconductor layer 140 in a pair. The ohmic contact members may bedisposed between the source and drain electrodes 165 and 166 and thesemiconductor layer 140, so that the source and drain electrodes 165 and166 and the semiconductor layer 140 can have ohmic contactcharacteristics. When the semiconductor layer 140 includes an oxidesemiconductor, the ohmic contact members may be omitted.

The data line 162, the source electrode 165, the drain electrode 166,and the storage electrode 168 are disposed on the semiconductor layer140 and the gate insulating film 130.

The data line 162 may extend in the second direction D2 and intersectthe gate line 122.

The data line 1.62 may be insulated from the gate line 122, the gateelectrode 124 and the storage line 125 by the gate insulating film 130.

The data line 162 may provide a data voltage to the source electrode165. Here, the data voltage may be provided from an external source andmay have a varying level. The gray level of each pixel 10 may changeaccording to the level of the data voltage.

The source electrode 165 may branch from the data line 162, and at leastpart of the source electrode 165 may overlap the gate electrode 124.

The drain electrode 166 may be separated from the source electrode 165with the semiconductor layer 140 interposed between them based on FIG.1, and at least part of the drain electrode 166 may overlap the gateelectrode 124.

The storage electrode 168 may be connected to the drain electrode 166through an area where a contact hole 173 is disposed, and may form acapacitance by overlapping the storage line 125.

The data line 162, the source electrode 165, the drain electrode 166,and the storage electrode 168 may be made of the same material. In anexample, the data line 162, the source electrode 165, the drainelectrode 166, and the storage line 125 may be made of aluminum, copper,silver, molybdenum, chromium, titanium, tantalum, or an alloy of thesematerials. In addition, each of the data line 162, the source electrode165, the drain electrode 166, and the storage line 125 may have amultilayer structure composed of a lower layer (not illustrated) made ofrefractory metal and an upper layer (not illustrated) made of a materialwith low resistivity.

The gate electrode 124, the semiconductor layer 140, the sourceelectrode 165, and the drain electrode 166 collectively constitute thethin-film transistor 167, which is a switching device.

A passivation film 171 is disposed on the gate insulating film 130 andthe thin-film transistor 167. The passivation film 171 may be made of aninorganic insulating material, and may cover the thin-film transistor167. The passivation film 171 may protect the thin-film transistor 167and prevent a material contained in an organic insulating film 172 fromflowing onto the semiconductor layer 140.

The organic insulating film 172 is disposed on the passivation film 171.The organic insulating film 172 may be made of an organic insulatingmaterial. The organic insulating film 172 may planarize steps formed bycomponents disposed between the organic insulating film 172 and thefirst base substrate 110. In other words, an upper surface of theorganic insulating film 172 may be substantially flat.

The contact hole 173 may be formed in the passivation film 171 and theorganic insulating film 172. The contact hole 173 may partially exposethe thin-film transistor 167, and more specifically may partially exposean upper surface of the drain electrode 166. The contact hole 173 maypass through the passivation film 171 and the organic insulating film172 in a direction perpendicular to the first base substrate 110. Aportion of the drain electrode 166 and the pixel electrode 191 disposedon the organic insulating film 172 may be physically connected to eachother through the contact hole 173.

A reflective electrode 181 is disposed on the organic insulating film172. The reflective electrode 181 may be disposed in an area other thanthe area where the contact hole 173 is formed in each pixel 10, andother than an area where a boundary between adjacent pixels 10 isformed.

The reflective electrode 181 reflects light, which is incident upon thefirst display substrate 100, back out of the second display substrate300. To reflect light, the reflective electrode 181 may be made of areflective opaque material such as Al, Ag, an Al alloy, or an Ag alloy.As the light reflectivity of the reflective electrode 181 is higher, theLCD may appear brighter.

The reflective electrode 181 may not have a pattern and may be formed tooverlap most of the area in each pixel 10, except the area where thecontact hole 173 is formed and the boundary between adjacent pixels 10.

The pixel electrode 191 is disposed on the reflective electrode 181. Thepixel electrode 191 may overlap most of the area in each pixel 10,except the boundary between adjacent pixels 10. Unlike the reflectiveelectrode 181, the pixel electrode 191 may overlap the area where thecontact hole 173 is disposed, may be physically connected to the drainelectrode 166 via the contact hole 173, and may thus receive the datavoltage from the drain electrode 166.

The pixel electrode 191 may be formed as a unitary structure thatoverlaps the area in each pixel 10 but does not have a pattern.Alternatively, in some embodiments, the pixel electrode 191 may have apattern including openings.

The pixel electrode 191 may be made of a transparent conductive materialsuch as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zincoxide (ITZ0), or Al-doped zinc oxide (AZO).

The second display substrate 300 will hereinafter be described.

The second display substrate 300 includes a second base substrate 310, acolor filter layer 320, an overcoat layer 330, and a common electrode340.

The second base substrate 310 is disposed opposite to the first basesubstrate 110. The second base substrate 310 may have durability towithstand external impacts. The second base substrate 310 may be atransparent insulating substrate. For example, the second base substrate310 may be a glass substrate, a quartz substrate, a transparent resinsubstrate, or the like. The second base substrate 310 may be shaped as aflat plate, but can also be curved in one or more specific directions.

The color filter layer 320 is disposed on a surface of the second basesubstrate 310 facing the first display substrate 100. The color filterlayer 320 may be a photosensitive organic composition containing apigment for realizing a color, and may include any one of red, green,and blue pigments. In an example, the color filter layer 320 may includea plurality of color filters. In an example, any one of the colorfilters may display any one of any primary colors, e.g., three primarycolors of red, green, and blue. However, the inventive concept is notlimited to this case, and any one of the color filters may also displayany one of cyan, magenta, yellow, and white colors.

For ease of description, a color filter disposed on the right side ofFIG. 2 will be defined as a first color filter 321, and a color filterdisposed on the left side of FIG. 2 will be defined as a second colorfilter 322. The first color filter 321 and the second color filter 322may display different colors, and each of the first color filter 321 andthe second color filter 322 may display various colors.

In the current embodiment, a boundary between the first color filter 321and the second color filter 322 is formed along the boundary of thepixel 10. More specifically, the boundary of the first color filler 321is formed along the data line 162. However, the first color filter 321and the second color filter 322 can be arranged in any manner as long asthe boundary between the first color filter 321 and the second colorfilter 322 extends at least approximately along the boundary of eachpixel 10.

The boundary between the first color filter 321 and the second colorfilter 322 may be formed by the overlap of part of an edge of the firstcolor filter 321 and part of an edge of the second color filter 322.Since each of the first color filter 321 and the second color filter 322is made of an organic material as described above, the boundary of eachof the first color filter 321 and the second color filter 322 may begentle. That is, the edge of the first color filter 321 and the edge ofthe second color filter 322 may partially overlap each other. Due tothis overlap of the first color filter 321 and the second color filter322, light components that can transmit through the first color filter321 and the second color filter 322 may be limited at the boundarybetween the first color filter 321 and the second color filter 322.Therefore, the boundary between the first color filter 321 and thesecond color filter 322 may look dark even without a member for blockinglight, such as a light blocking member.

Although the boundary between the first color filter 321 and the secondcolor filter 322 looks dark, light may not be completely blocked at theboundary due to the absence of the light blocking member. Therefore,colors of light components passing through both the first color filter321 and the second color filter 322 can be mixed. However, such colormixture can be prevented or minimized by a protruding pattern 350 andreflective members 360 which will be described later.

The overcoat layer 330 is disposed on a surface of the color filterlayer 320 facing the first display substrate 100. The overcoat layer 330may reduce a step formed by the color filter layer 320. In someembodiments, the overcoat layer 330 may be omitted.

The common electrode 340 is disposed on a surface of the overcoat layer330 facing the first display substrate 100. The common electrode 340 maybe made of a transparent conductive material such as ITO, IZO, ITZO, orAZO.

The common electrode 340 may be formed as a continuous layer over theentire surface of the second base substrate 310. That is, the commonelectrode 340 may be formed as a unitary layer that is disposed over thepixels 10 and includes no openings having a specific pattern.

A common voltage provided from an external source may be applied to thecommon electrode 340. Accordingly, the common electrode 340 may form anelectric field in the liquid crystal layer 200 together with the pixelelectrode 191. Here, the common voltage may be provided from theexternal source, and the level of the common voltage may be keptconstant during the operation of the LCD. Hence, an electric field maybe formed where the pixel electrode 191 and the common electrode 340overlap each other, due to a difference between the level of the datavoltage applied to the pixel electrode 191 and the level of the commonvoltage applied to the common electrode 340. The electric field maycause the liquid crystals 210 to be rotated or tilted.

The protruding pattern 350 may be formed on a surface of the commonelectrode 340 facing the first display substrate 100. The protrudingpattern 350 may have a specific height, and may be disposed along theboundary between the first color filter 321 and the second color filter322. The cross-sectional structure of the protruding pattern 350 mayhave a convex shape having a larger width closer to the second basesubstrate 310 and a smaller width farther from the second base substrate310. In other words, sidewalls of the protruding pattern 350 may have aninclination angle of 90 degrees or less with respect to the second basesubstrate 310. More specifically, the sidewalls of the protrudingpattern 350 may have an inclination angle of 20 to 90 degrees. Here, thesidewalls of the protruding pattern 350 may form a gentle slope asillustrated in FIG. 2, and may form a linear slope that makes thecross-sectional structure of the protruding pattern 350 have atrapezoidal shape or a triangular shape.

The protruding pattern 350 may not overlap the reflective electrode 181.As will be described later, the reflective members 360 may be disposedon the sidewalls of the protruding pattern 350 to block the transmissionof light and to reflect light. Therefore, the protruding pattern 350 isdisposed to not overlap the reflective electrode 181, thereby minimizinga reduction in transmittance. The protruding pattern 350 may be made ofa transparent organic material.

The reflective members 360 are disposed on the sidewalls of theprotruding pattern 350. The reflective members 360 may partially coverthe sidewalls of the protruding pattern 350 and may extend along adirection in which the protruding pattern 350 extends.

The reflective members 360 may be made of a metallic material thatreflects light, such as Al, Ag, an Al alloy, or an Ag alloy. However,the material of the reflective members 360 is not limited to theseexamples, and the reflective members 360 can also be made of other knownmaterials that reflect light.

A reflective member 360 may be disposed on a sidewall of the protrudingpattern 350, and another reflective member 360 may be disposed on anopposing sidewall of the protruding pattern 350. In other words, a pairof the reflective members 360 may be arranged on one protruding pattern350 and may be physically separated and insulated from each other.However, when the reflective members 360 have electrical conductivity,they can be electrically connected to each other by the common electrode340.

In the cross-sectional view of FIG. 2, the reflective members 360 andthe common electrode 340 are physically connected to each other.However, the reflective members 360 and the common electrode 340 canalso be separated from each other. When the reflective members 360 andthe common electrode 340 are physically connected to each other and whenthe reflective members 360 have electrical conductivity, an electricfield is formed in the liquid crystal layer 200 not only by the commonelectrode 340 but also by the reflective members 360. Therefore, theelectric field can be distorted. However, the distortion of the electricfield can be prevented by separating the reflective members 360 from thecommon electrode 340.

The protruding pattern 350 and the reflective members 360 can prevent orminimize the color mixture that may occur at the boundary between thefirst color filter 321 and the second color filter 322.

Specifically, light incident along a first light path L1 in FIG. 2passes through the first color filter 321 and is reflected by thereflective electrode 181. Then, the light passes through the first colorfilter 321 again and is emitted to the outside of the second displaysubstrate 300. Therefore, since the light traveling along the firstlight path L1 passes through only the first color filter 321, there isno concern about color mixture.

On the other hand, light incident along a second light path L2 in FIG. 2passes through the first color filter 321 and is reflected by thereflective electrode 181. Then, the light proceeds toward the secondcolor filter 322 instead of passing through the first color filter 321again. Here, without the protruding pattern 350 and the reflectivemembers 360, the light incident along the second light path L2 would bereflected by the reflective electrode 181 and then pass through thesecond color filter 322 to be emitted to the outside of the seconddisplay substrate 300. In this case, color mixture can occur. However,since the protruding pattern 350 and the reflective members 360 areprovided, the light incident along the second light path L2 is reflectedby the reflective electrode 181 and then reflected again by thereflective members 360. Then, the reflected light passes through thefirst color filter 321 and is emitted to the outside of the seconddisplay substrate 300. Thus, color mixture can be prevented or minimizedat the boundary between the first color filter 321 and the second colorfilter 322.

The liquid crystal layer 200 will hereinafter be described.

A plurality of liquid crystals 210 may be arranged in the liquid crystallayer 200. When an electric field is formed between the first displaysubstrate 100 and the second display substrate 300, the liquid crystals210 may rotate or tilt in a specific direction between the first displaysubstrate 100 and the second display substrate 300, thereby changing thepolarization of light.

The liquid crystals 210 may be arranged in a 90-degree twisted mannerbetween the first display substrate 100 and the second display substrate300 facing each other. That is, twisted nematic (TN) mode liquidcrystals 210 may be arranged. However, the alignment mode of the liquidcrystals 210 is not limited to the TN mode. Instead, various alignmentmodes can be used, such as a vertical alignment mode in which the liquidcrystals 210 are arranged vertically between the first display substrate100 and the second display substrate 300 using a vertical alignmentfilm, and an in-plane switching (IPS) mode in which the liquid crystals210 are arranged and switched horizontally.

A method of manufacturing the protruding pattern 350 and the reflectivemembers 360 of the LCD according to the current embodiment willhereinafter be described.

FIG. 3, FIG. 4, FIG. 5 and FIG. 6 are cross-sectional views illustratinga method of manufacturing an LCD according to an embodiment.

FIG. 3, FIG. 4, FIG. 5 and FIG. 6 correspond to cross-sectional views ofthe second display substrate 300 taken along the line I-I′ of FIG. 1. InFIG. 2, the second display substrate 300 is placed to face the firstdisplay substrate 100. Therefore, the second display substrate 300 isdisposed in an upper part in FIG. 2. However, since FIG. 3, FIG. 4, FIG.5 and FIG. 6 illustrate only the second display substrate 300, thesecond display substrate 300 of FIG. 2 may be rotated by 180 degrees.

The process of manufacturing an LCD can be largely divided as follows.That is, after a first display substrate 100 and a second displaysubstrate 300 are separately manufactured, they may be placed to faceeach other. Then, a liquid crystal layer 200 may be injected between thefirst display substrate 100 and the second display substrate 300, and agap between the first display substrate 100 and the second displaysubstrate 300 may be sealed. The cross-sectional views of FIG. 3, FIG.4, FIG. 5 and FIG. 6 illustrate part of the process of manufacturing thesecond display substrate 300 in the process of manufacturing an LCD.Specifically, a method of manufacturing a protruding pattern 350 andreflective members 360 according to an embodiment will be mainlydescribed.

Referring to FIG. 3, a color filter layer 320 is formed on a second basesubstrate 310. Each color filter included in the color filter layer 320may be formed by a different mask process. That is, a first color filter321 may be formed by a first mask process, and a second color filter 322may be formed by a second mask process.

In the following description, the term “mask process” denotes apatterning process performed using a photomask. One unit mask processincludes an exposure and development process, and may further include anetching process.

Next, an overcoat layer 330 is formed on the color filter layer 320. Theovercoat layer 330 may be a laminated film of an organic material andmay be formed by chemical vapor deposition, sputtering, or other knownprocesses.

Next, a common electrode 340 is formed on the overcoat layer 330.

Next, a photosensitive organic material layer 351 is formed on the firstbase substrate 110 having the color filter layer 320, the overcoat layer330, and the common electrode 340.

Referring to FIG. 4, the photosensitive organic material layer 351 isexposed to ultraviolet light through a mask having a pattern, anddeveloped to form the protruding pattern 350. The photosensitive organicmaterial layer 351 is made of a material that undergoes a polymerizationreaction or decomposition reaction when exposed to light of apredetermined wavelength. The photosensitive organic material layer 351may be of a negative type in which a chemical is insoluble by exposure,or a positive type in which the chemical is soluble by exposure. Eitherof the negative type or the positive type can be selected. The exposurecan be performed by a photolithography process.

In other words, the protruding pattern 350 is formed through one maskprocess.

Referring to FIG. 5, a reflective member material layer 361 is formed onthe common electrode 340 and the protruding pattern 350.

Referring to FIG. 6, one mask process of coating a photosensitivematerial on the reflective member material layer 361, exposing anddeveloping the photosensitive material, and then etching the,photosensitive material to form patterns of the reflective members 360is performed. That is, the reflective members 360 are formed onsidewalls of the protruding pattern 350 by one mask process.

Finally, an LCD is manufactured by using the second display substrate300 manufactured through the processes of FIG. 3, FIG. 4, FIG. 5 andFIG. 6, and the first display substrate 100 manufactured separately fromthe second display substrate 300.

Although the protruding pattern 350 and the reflective members 360 havebeen described as being formed by a mask process, they can also bemanufactured by other known processes. In an example, the protrudingpattern 350 and the reflective members 360 can be formed by an inkjetprocess.

FIG. 7 is a cross-sectional view of an LCD according to an embodiment,taken along the line I-I′ of FIG. 1.

The LCD according to the current embodiment is different from the LCD ofFIG. 2 in that a protruding pattern 192 a and reflective members 193 aare disposed not in a second display substrate 300 a but in a firstdisplay substrate 100 a. Therefore, a description of reference numeralsand components identical or similar to those of FIG. 2 will be omitted,and the LCD according to the current embodiment will be described,focusing mainly on differences from the LCD of FIG. 2.

Referring to FIG. 7, in the LCD according to the current embodiment, theprotruding pattern 192 a and the reflective members 193 a are disposedon an organic insulating film 172. More specifically, the protrudingpattern 192 a and the reflective members 193 a may be disposed on anexposed upper surface of the organic insulating film 172 or on an uppersurface of a pixel electrode 191 of the first display substrate 100 a.

The arrangement of the protruding pattern 192 a and the reflectivemembers 193 a in plan view may be the same as the arrangement describedabove with reference to FIG. 1. Accordingly, the contribution of theprotruding pattern 192 a and the reflective members 193 a to minimizingor preventing color mixture may be the same as that described above withreference to FIGS. 1 and 2. That is, the protruding pattern 192 a andthe reflective members 193 a can be formed in any one of the firstdisplay substrate 100 a and the second display substrate 200 a.

In addition, a method of manufacturing the protruding portion member 192a and the reflective members 193 a disposed in the first displaysubstrate 100 a may be the same as the manufacturing process describedabove with reference to FIG. 3, FIG. 4, FIG. 5 and FIG. 6.

FIG. 8 is a cross-sectional view of an LCD according to an embodiment,taken along the line I-I′ of FIG. 1.

The LCD according to the current embodiment is different from the LCD ofFIG. 7 in that a protruding pattern and an organic insulating film areintegrally formed and that reflective members and a reflective electrodeare integrally formed. Therefore, a description of reference numeralsand components identical or similar to those of FIG. 7 will be omitted,and the LCD according to the current embodiment will be described,focusing mainly on differences from the LCD of FIG. 7.

Referring to FIG. 8, an organic insulating film 172 b of the LCDaccording to the current embodiment includes a flat portion 172 b_1 anda protruding portion 172 b_2. The flat portion 172 b_1 is disposed on apassivation film 171 and refers to a portion of the organic insulatingfilm 172 b in an area (where an upper surface of the organic insulatingfilm 172 b is flat) other than an area where a contact hole 173 isdisposed. On the other hand, the protruding portion 172 b_2 refers to apattern protruding upward (based on FIG. 8) from the flat portion 172b_1 toward the second display substrate 300 a. The protruding portion172 b_2 may have the same shape and perform the same function as theprotruding pattern 192 a of FIG. 7.

In addition, a reflective electrode 181 b of the LCD according to thecurrent embodiment includes a first reflective portion 181 b_1 andsecond reflective portions 181 b_2.

The first reflective portion 181 b_1 reflects light incident fromoutside a second display substrate 300 a, such that the light can beemitted back to the outside of the second display substrate 300 a. Thefirst reflective portion 181 b_1 may perform the same function as thereflective electrode 181 described above with reference to FIG. 1 andFIG. 2.

The second reflective portions 181 b_2 may extend from the firstreflective portion 181 b_1 and may be disposed along sidewalls of theprotruding portion 172 b_2 of the organic insulating film 172 b toreflect light. The second reflective portions 181 b_2 may perform thesame function as the reflective members 360 described above withreference to FIG. 1 and FIG. 2.

Although the organic insulating film 172 b includes the flat portion 172b_1 and the protruding portion 172 b_2 and the reflective electrode 181b includes the first reflective portion 181 b_1 and the secondreflective portions 181 b_2, the planar and cross-sectional structuresof the protruding portion 172 b_2 and the second reflective portions 181b_2 may be substantially the same as those of the protruding pattern 192a and the reflective members 193 a described above with reference toFIG. 7. Accordingly, the contribution of the protruding portion 172 b-2and the second reflective portions 181 b_2 to minimizing or preventingcolor mixture may be the same as that described above with reference toFIG. 7.

Further, in the structure of the LCD according to the currentembodiment, no additional mask process is required to implementstructures similar to the protruding pattern 192 a and the reflectivemembers 193 a of FIG. 7. Thus, costs can be saved. This will now bedescribed in detail with reference to FIG. 9, FIG. 10, FIG. 11 and FIG.12.

FIG. 9, FIG. 10, FIG. 11 and FIG. 12 are cross-sectional viewsillustrating a method of manufacturing an LCD according to anembodiment.

FIG. 9, FIG. 10, FIG. 11 and FIG. 12 correspond to cross-sectional viewsof a first display substrate 100 b taken along the line I-I′ of FIG. 1.

First, referring to FIG. 9, a gate electrode 124 is formed on a firstbase substrate 110. The gate electrode 124 is formed by one maskprocess. Next, a gate insulating film 130 is formed. The gate insulatingfilm 130 may be made of silicon nitride, silicon oxide, or a laminatedfilm of these materials, and may be formed by chemical vapor depositionor sputtering. Next, a semiconductor layer 140, a source electrode 165,and a drain electrode 166 are formed. The semiconductor layer 140, thesource electrode 165, and the drain electrode 166 may be formed by asingle mask process. Next, a passivation film 171 is formed.

Next, an organic insulating material layer 173 b is formed on thepassivation film 171.

Referring to FIG. 10, the organic insulating material layer 173 b isexposed to ultraviolet light through a mask having a pattern, and isthen developed to form an organic insulating film 172 b including a flatportion 172 b_1, a protruding portion 172 b_2 and a contact hole 173.

Here, the mask may be a halftone mask or a slit mask, and a differentamount of light may be irradiated to each area of the organic insulatingmaterial layer 173 b in the exposure process. That is, the amount oflight irradiated to an area where the protruding portion 172 b_2 isformed may be different from the amount of light irradiated to an areawhere the flat portion 172 b_1 is formed and to the amount of lightirradiated to an area where the contact hole 173 is formed.

Referring to FIG. 11, a reflective electrode material layer 183 b isformed on the organic insulating film 172 b including the flat portion172 b_1 and the protruding portion 172 b_2.

Referring to FIG. 12, one mask process is performed. In the maskprocess, a photosensitive material is coated on the reflective electrodematerial layer 183 b, exposed and developed, and then etched to form areflective electrode 181 b which includes a first reflective portion 181b_1 and second reflective portions 181 b_2.

Finally, an LCD may be manufactured by using the first display substrate100 b manufactured through the processes of FIG. 9, FIG. 10, FIG. 11 andFIG. 12, and a second display substrate 300 a manufactured separatelyfrom the first display substrate 100 b.

Therefore, if the processes of FIG. 9, FIG. 10, FIG. 11 and FIG. 12 areperformed, the LCD of FIG. 8 having the same structures as theprotruding pattern 192 a and the reflective members 193 a illustrated inFIG. 7 can be manufactured without requiring more than the number ofmask processes required to manufacture a conventional LCD. Thus, costscan be reduced.

According to embodiments, an LCD in which color mixture is minimized canbe provided.

However, the effects of the inventive concept are not restricted to theone set forth herein. The above and other effects of the inventiveconcept will become more apparent to one of daily skill in the art towhich the inventive concept pertains by referencing the claims. Variousfeatures of the above described and other embodiments can be mixed andmatched in any manner, to produce further embodiments consistent withthe invention.

What is claimed is:
 1. A liquid crystal display (LCD) comprising: afirst display substrate; a second display substrate which faces thefirst display substrate; and a liquid crystal layer which is disposedbetween the first display substrate and the second display substrate,wherein the first display substrate comprises a first base substrate, areflective electrode which is disposed on the first base substrate, anda pixel electrode which is disposed on the reflective electrode; whereinthe second display substrate comprises: a second base substrate, a colorfilter layer which comprises a first color filter disposed on a surfaceof the second base substrate which faces the first base substrate, and asecond color filter configured to display a different color from that ofthe first color filter, a protruding pattern which is formed on asurface of the color filter layer facing the first base substrate, andwhich extends along a boundary between the first color filter and thesecond color filter, and reflective members which are disposed onsidewalls of the protruding pattern.
 2. The LCD of claim 1, wherein twoof the reflective members are separated from each other.
 3. The LCD ofclaim 1, wherein a cross-sectional width decreases with distance fromthe second base substrate.
 4. The LCD of claim 1, wherein the protrudingpattern comprises an organic material.
 5. The LCD of claim 1, whereinthe pixel electrode is a light transmissive electrode.
 6. The LCD ofclaim 1, wherein the boundary between the first color filter and thesecond color filter is formed by an overlap between the first colorfilter and the second color filter.
 7. The LCD of claim 6, wherein awidth of the protruding pattern is greater than a width of the overlap.8. The LCD of claim 1, wherein an inclination angle between the surfaceof the second base substrate and the sidewalls of the protruding patternis in the range of 20 to 90 degrees.
 9. The LCD of claim 1, wherein thereflective electrode and the protruding pattern do not overlap eachother in plan view.
 10. The LCD of claim 1, wherein the reflectivemembers are formed by a photolithography process or an inkjet process.11. The LCD of claim 1, wherein the first display substrate furthercomprises an insulating film which is disposed between the reflectiveelectrode and the pixel electrode and which electrically insulates thereflective electrode from the pixel electrode.
 12. An LCD comprising: afirst display substrate: a second display substrate which faces thefirst display substrate; and a liquid crystal layer which is disposedbetween the first display substrate and the second display substrate,wherein the first display substrate comprises a first base substrate, areflective electrode which is disposed on the first base substrate, apixel electrode which is disposed on the reflective electrode, aprotruding pattern which is disposed on the pixel electrode, andreflective members which are disposed on sidewalls of the protrudingpattern, wherein the second display substrate comprises: a second basesubstrate, and a color filter layer which comprises a first color filterdisposed on a surface of the second base substrate which faces the firstbase substrate, and a second color filter configured to display adifferent color from that of the first color filter, and wherein theprotruding pattern extends along a boundary between the first colorfilter and the second color filter.
 13. The LCD of claim 12, wherein twoof the reflective members are separated from each other.
 14. The LCD ofclaim 12, wherein the boundary between the first color filter and thesecond color filter is formed by an overlap between the first colorfilter and the second color filter.
 15. An LCD comprising: a firstdisplay substrate: a second display substrate which faces the firstdisplay substrate; and a liquid crystal layer which is disposed betweenthe first display substrate and the second display substrate, whereinthe first display substrate comprises a first base substrate, an organicfilm which is disposed on the first base substrate and which comprises aflat portion having a flat upper surface and a protruding portionprotruding from the flat portion toward the second display substrate, areflective electrode which comprises a first reflective portion disposedon the flat portion and second reflective portions disposed on sidewallsof the protruding portion, and a pixel electrode which is disposed onthe reflective electrode, and wherein the second display substratecomprises a second base substrate, and a color filter layer whichcomprises a first color filter disposed on a surface of the second basesubstrate that faces the first base substrate and a second color filterconfigured to display a different color from that of the first colorfilter.
 16. The LCD of claim 15, wherein the protruding portion extendsalong a boundary between the first color filter and the second colorfilter.
 17. The LCD of claim 16, wherein the boundary between the firstcolor filter and the second color filter is formed by an overlap betweenthe first color filter and the second color filter.
 18. The LCD of claim15, wherein the pixel electrode is a light transmissive electrode. 19.The LCD of claim 15, wherein two of the second reflective portions areseparated from each other.
 20. The LCD of claim 15, wherein the organicfilm is formed using a halftone mask.